High efficiency entrapment of superoxide dismutase into mucoadhesive chitosan-coated liposomes

Superoxide dismutase (SOD), antioxidative enzyme and potential anti-inflammatory agent, was encapsulated into mucoadhesive chitosan-coated liposomes in order to increase its releasing time and to facilitate its cellular penetration. Positively, neutrally and negatively charged liposomes were prepared using soybean lecithin, stearylamine, phosphatidyl glycerol and cholesterol. The effects of liposomal lipid composition and protein to lipid ratio on the encapsulation parameters were studied in three preparation methods: dehydration–rehydration, hydration and proliposome methods. The highest efficiency of SOD entrapment, 39–65%, was achieved by the proliposome method. Vesicles prepared by the hydration method entrapped 1–13% and vesicles prepared by dehydration–rehydration entrapped 2–3% of SOD. Stability tests for SOD-loaded liposomes prepared by the proliposome method showed no significant loss of the enzyme activity within 1 month at 4 °C or within 2 days at 37 °C. Positively, neutrally and negatively charged liposomes, prepared by the proliposome method, were successfully coated with two types of low and medium molecular weight chitosans. Both types of chitosan coating increased the mucoadhesive characteristics of all three types of vesicles. Using the proliposome method and subsequent chitosan coating, highly efficient SOD-loaded vesicles for drug targeting on mucosal tissues could be produced.     

黄芩前体脂质体再复水后的新脂质体粒径研究

用超声波法或高压乳化法等制备黄芩脂质体分散液,该脂质体粒径50～90 nm,包封率和回收率均达100%。用流动床将它向各种糖类芯料(山梨醇、葡萄糖、甘露糖、蔗粒、乳糖等)作切线喷雾制成粉末——黄芩前体脂质体。在喷雾过程和再复水过程中,原脂质体的有效碰撞几率可因非挥发性高沸点介质而减少,再复水溶媒中的磷酸根离子会使新脂质体粒径增大。减少或控制这些因素可制得性质稳定、不易氧化的黄芩前脂质体,其再复水形成的新脂质体粒径在100 nm左右,符合注射要求。     

A novel formulation of [6]-gingerol: Proliposomes with enhanced oral bioavailability and antitumor effect

[6]-Gingerol, one of the components of the rhizome of Ginger, has a variety of biological activities such as anticoagulant, antioxidative, antitumor, anti-inflammatory, antihypertensive, and so forth. However, as one of the homologous phenolic ketones, [6]-gingerol is insoluble in water which limits its applications. Herein, we prepared [6]-gingerol proliposomes through modified thin-film dispersion method, which was spherical or oval, and physicochemically stable with narrow size distribution. Surprisingly, in vitro release of [6]-gingerol loaded proliposome compared with the free [6]-gingerol was significantly higher and its oral bioavailability increased 5-fold in vivo. Intriguingly, its antitumor effect was enhanced in the liposome formulation. Thus, our prepared [6]-gingerol proliposome proved to be a novel formulation for [6]-gingerol, which significantly improved its antitumor effect.     

前体脂质体的制备及携载青霉素趋脑组织的研究

采用旋转蒸发法制备了青霉素前体脂质体，并对其趋脑组织进行了观察，前体脂质体很稳定，制备过程中药物含量无明显降低，３０天内室温存放开渗漏，同时对脑组织具有趋向性，可以携带药物透过血管屏障进入脑组织。     

Synergistic absorption enhancement of salmon calcitonin and reversible mucosal injury by applying a mucolytic agent and a non-ionic surfactant

Using high sensitivity differential scanning calorimetry (HSDSC), the phase transitions of dimyristoylphosphatidylcholine (DMPC) liposomal bilayers and their interaction with the model steroid beclometasone dipropionate (BDP) were found to be dependent on the method of liposome manufacture. Ethanol-based proliposomes produced liposomes having no phospholipid pretransition, a main transition of high enthalpy and a low onset temperature, and a very low incorporation of the steroid (maximum 1 mol%). This was attributed to an alcohol-induced interdigitation of the bilayers, which was not apparently reversed by flushing the liposome dispersion with nitrogen in an attempt to remove ethanol. For liposomes manufactured by thin film or particulate-based proliposome methods, 1–2.5 mol% steroid was optimal for incorporation within bilayers, although the nature of the steroid interaction with the bilayers differed between the two methods. For liposomes manufactured by the thin film method, a higher steroid concentration resulted in a broadened main transition and a reduced melting cooperativity. This suggests that BDP formed separate domains within the bilayers which caused non-ideal mixing and phase separation at 5 mol% steroid. This observation was absent for liposomes generated from particulate-based proliposomes, indicating separate steroid domains were not formed and subsequent non-ideal mixing and phase separation did not occur. In addition, liposomes generated from particulate-based proliposomes showed reduced pretransition and main transition enthalpies. These differences were attributed to the employment of sucrose to manufacture the particulate-based proliposomes. This study has shown that the thermal behaviour of liposomes and their interaction with beclometasone dipropionate were dependent on the method of liposome manufacture. Moreover, particulate-based proliposomes may provide a reasonable alternative to the conventional thin film method in producing liposomes incorporating this steroid.     

灯盏花素前体脂质体胶囊突释的评价方法

目的：建立灯盏花素前体脂质体胶囊的突释考察方法。方法：采用透析-高效液相色谱法（HPLC），水化前体脂质体后，用透析袋分析游离药物和脂质体，并用HPLC法测定含量。采用Diamonsil ODS C18色谱柱（4.6mmx250mm，5μm），流动相为甲醇-乙腈-40mmol／LKH2P04（磷酸调pH至2．5）（18：12：70）；检测波长335nm；流速1．0ml／min；柱温35℃。结果：游离药物在透析膜两侧均匀分布，而脂质体被截留于透析袋中。含量测定方法平均加样同收率为103．32％，RSD为1．12％（n=9）。结论：本法操作简便、准确，可用于灯盏花素前体脂质体胶囊突释的评价。     

In Situ Liposomal Preparation Containing Amphotericin B: Related Toxicity and Tissue Disposition Studies

The purpose of this research was to develop a novel hydroalcoholic method for the preparation of liposome entrapping inclusion complex of amphotericin B (AmB) with a view to obtaining reduced toxicity and superior tissue distribution of AmB in vivo. The method involves initial preparation of AmB–hydroxypropyl-β-cyclodextrin (AmB–HPBCD) intercalated proliposome which is subsequently converted into a liposome dispersion by single dilution method. The AmB–liposome (L-AmB) derived from proliposome exhibited a superior entrapment efficiency (94.8 ± 0.7%) compared to liposomes prepared by employing a conventional solvent-based technique (89.7 ± 2.9%). The dose that was lethal to 50% of subjects (LD₅₀) (mg/kg) value of AmB contained in stabilized proliposome-based liposomes was 18.6 ± 0.25, whereas that in conventional solvent-based liposomes was 7.8 ± 0.25. Incorporation of AmB–HPBCD into hydroalcoholic liposomes enhanced antifungal activity in experimental aspergillosis in Balb/c mice in vivo: 80% survival was recorded after 7 days of therapy and the fungal load in lung was reduced. The results clearly demonstrate that preferential uptake of L-AmB entrapped inclusion complex (AmB–HPBCD) by the reticulo endothelial system correlated with diminished levels of AmB in infected (p > 0.05) and noninfected (p > 0.001) kidney after 24 hr compared to that observed with conventional solvent-based L-AmB. Therefore, proliposome-based liposome entrapping inclusion complex of AmB with HPBCD offered an improved therapeutic efficacy by lowering toxicity as well as by altering the tissue distribution pattern.